Cooling system for x-ray apparatus



Feb. 23, 1965 c. E. BOUCHER 3,171,029

COOLING SYSTEM FOR X-RAY APPARATUS Filed Feb. 26. 1962 //V VE/V TOR CORMACK E. BOUCHER Z2 By 9 BUCKHORN, CHEATHAM a BLORE 3 ATTORNEYS United States Patent 3,171,629 CGGLING SYSTEM FQR X-RAY APPARATUS ilonnaelr E. Beecher, Seattle, Wash., assignor; to Indi tCorporation, Seattle, Wash, a corporation at Washington Filed Feb. 26, 1962, tier. No. 175,662 6 Claims. (Cl. 250-459) The present invention relates to X-ray apparatus and more particularly to an arrangement for cooling an X-ray tube.

As is well known, copious amounts of heat are generated in the anode of an X-ray tube during its operation and the ability to remove such heat is frequently a limiting factor in the operation of the tube. Cooling systems of circulating fluid are frequently utilized but such systems as heretofore provided are frequently troubled with mechanical breakdown of the pump.

It is, therefore, an object of the present invention to provide a cooling arrangement for an X-ray tube which is not subject to mechanical breakdown. p

More particularly, it is an object of the'present invention to provide a circulating fluid cooling system for an X-ray tube utilizing anion drag pump to elfect circulation of fluid.

Still another object of the present invention is to 'provide a new and improved X-ray apparatus including a fluid circulating system for removing heat from the X-ray tube and in which the high voltage transformer supplying accelerating potential to the electrodes of the X-ray tube is utilized to supply accelerating potential to an ion drag pump effecting circulation of fluid in such system.

Another object of the invention is to provide an X-ray apparatus and fluid circulating system of the type described above wherein the'X-ray tube is utilized as a rectifier to supply DC. potential to the ion dragpump.

Other objects and advantages of the invention will become more apparent hereinafter.

For a more detailed description of the invention reference is made to the following specification and the accompanying drawings, wherein:

FIG. 1 is a sectional elevation of X-ray apparatus made in accordance with the invention;

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1.

FIG. 3 is a sectional view taken along line 33 of FIG. 2;

FIG. 4 is a schematic View of an electrical circuit for the apparatus of the invention; and

FIG. 5 is a schematic view of a preferred embodiment of the circuit of the invention.

Referring now to the drawings, the invention is illustrated in connection with X-ray apparatus including a sealed, tubular housing including a generally cylindrical portion 12 and removable end domes 14, 16.

The housing It may be of magnesium or other suitable lightweight material.

Mounted within the housing 10 is a transformer having a rectangular core 19 and windings or coils 20, 21. Suitable leads 22, see FIGS. 4 and 5, are provided to connect the transformer to an external source of AC. power. Suitably supported between the windings 20, 21 is an X-ray generator or tube 24 comprising a suitable sealed envelope 26 in which are mounted an anode 28 3,171,029 Eatented Feb. 23, 1965 "Ice exchanger 40 to remove heat from the anode which exchanger may be of any known type and may comprise, for example, a conduit 41 of copper or other suitable material arranged in close association or contact with the anode stem 42 which extends exteriorly of the envelope '26. An insulating shield 46 may be positioned between the heat exchanger and the housing 10. Suitably supported upon the end dome 16 is a coil type radiator 50 connected to the heat exchanger4tl by conduits 52, 54 of Teflon or other electrically non-conductive material which pass through the dome 16 through suitable seals 55. The radiator 5b is protected by a perforated shell 56 suitably secured to the end of the tank 16. r A fan 58 preferably is provided to cause circulation'of air through the shell and past the radiator 50.

In accordance with the invention circulation from the heat exchanger 40 to the radiator 50 and return is attained by means of an ion drag pump 60 installed in the conduit line 54. The pump 60 comprises a cylindrical casing 62 of a suitable insulating material and an ion emitter 64 and a collector 66' mounted in spaced relation. The ion emitter 64 comprises an electrically conductive plate perforated-to permit fiuid flow therethrough and has'mounted on one surface thereof a'plurality of needles 68 which define corona discharge points.

The collector 66 is spaced downstream from the emitter 64 in the desiredv direction of fluid flow, and has a plu- Y rality of openings 70 preferably axially alignedone with each of the corona discharge points 68; The coolant system is" filled with a fluid of high dielectric strength and preferably with a liquid'dielectric such as transformer oil, kerosene or a liquid fluoro chemical.

As will be understood the application of a high negative potential to the emitter 64 will cause corona discharge to occur at the points 68 eiiecting a generation of ions which will be attracted toward the positive collector 66, a large proportion of the ions passing through the openings '70 because of their high velocity and falling back to the collector 66 on the far side thereof. In their movement the ions will induce a flow of coolant fluid in the direction from the emitter 64 to the collector 66 and will also induce flow of the fluid through the openings 70 in the collector plate to initiate circulation of all of the fluid in the system in the direction of movement of the ions so that the fluid will flow through the heat exchanger 40 to the radiator 50 and thence back to the ion drag pump 60.

It will be understood that the ion pump electrodes 64, 66 may be supplied with AC. potential directly from the transformers 20, 21 but the application of DC potential results in greater pumping efliciency.

Referring now to FIGURE 4, in accordance with one embodiment of the invention the X-ray tube 24 is utilized as a halfwave rectifier in a circuit to supply pulsating direct current to the ion drag pump. In accordance with this arrangement a voltage dropping resistor 71 is placed J in the line 32' between the anode 28' and the transformer 20.

The leads 72, 74 connect the collector and emitter, respectively, to the opposite ends of the resistor 71 so that a positive potential is supplied to the collector 66 and a negative potential (with respect to the collector) to the emitter 64.

A preferred embodiment 30f the invention is shown in IfIG, wherein a bridge rectifier 80 suppliedfrom a tap ,82 on thetransformer ZO is utilized to supply .a steady "11C, potential to the, ion pump electrodes 64,66. The steady. potential supplied by. such .a rectifier results inan increase inthe efficiency of the ion pump and thus better circulation o fthe fluid. I t o v I An X ray. tube cooling systern constructed in accordance withthe invention has a number ofadvantages. ,The ion pump 60 is of course exceedinglywsimple incon' ,s tr uction, is vsilentin its operation and'havingno moving parts is not subject to mechanical breakdown. It, can ,imoreover, if desired, be placed at elevated voltages above fgrour dvandv be-,e xcited by a portion ofsuch voltage. Moreovcr, the power consumption of the ion pump is for allj'practical purposes negligible. s QI-Iaving; illustrated and {described I certain preferred 1 embodiments ofthe presentinvention, it should be apparentto thoseskilled'inthe art .that. the.invention permits j ofjmodification in arrangement and'detaiLf I claim as my invention alLsuchfmodifications as come Within the true.

'spiritand scope of theappended claims.

IclaimL, V 1

l Lf'An ,X-ray. apparatus comprising an X-ray generator comprising .a cathode. and an anod e,

a ,high voltagetransformer for supplying accelerating potential to :saidgenerator, I I v a, cooling system for removing heat from said anode comprising a fluid circulatory system including a radiator, H 3 V g 4 a heat exchanger operatively associated with said anode to exti act heat from the latter c an iorr drag pump comprising an' emitter means and a e tq eans 1. 1 conduit meansconnecting said radiator, said heat exchanger and said ion drag pump in a closed series -ci rcuit, o v a dielectricvfiuid filling said system,

and means supplied from the secondary of. said high voltage, transformer for supplying a high'D. C.,.voltageto saidemitte means anda collector means. 2.; An X-ray apparatus comprising a sealed housing,

an X-ray tube inv said housing, a saidrX-raytube comprising a sealed envelope and a cathode and, an anode, r

ahigh voltage ,transformer. in said housing for supplying acceleratingjpotential, to, said tube, said-;anode comprising a stem extending outwardly'ot said envelope, 1 a cooling syste nfor removing ,heat from said anode stem and. transmitting the same exteriorly of .said l-housing comprising a fluid circulatory system inc-lud- .ln T a radiatorfpositioned ,exteriorly of said housing,

a heat exchanger operatively associated with said anode stem to extract heat from the latter, anion drag pump comprising an emitter means and a collector means,

conduit means connecting saidradiator, said heat exchanger 'and said ion drag pump in a' closed series circuit, said conduit, means extending through the housihg walt andbeing sealed therein, v

a fluidof high diele c'tric strength filli'ng said system, an electrical resistor in series with said anode and said transformer, 'and means connecting said emitter me'ans and said collector means across said resistor.

3. An X-ray apparatus comprising an X-ray generator comprising a cathode and an anode,

a high voltage transformer in said housing for supplying accelerating potential to said generator,

a cooling system for removing heat from said anode comprising a fluid circulatory system including a radiator,

a heat exchanger operatively associated with said anode to extract heat from the latter,

an ion drag pump comprising an emitter means and a collector means, v

and condiutmeans connecting said radiatonsaid heat exchanger and said ion drag pump in a closed series circuit, v V

a dielectric fluid filling said system,

and means supplied from the secondary of said high voltage, transfor ner for supplying a high voltage to saidemitter, means and collector means. 7

4. An X-ray apparatus comprising a sealed housing,

an X-ray tubein said housing, c

said tube comprising a sealed envelope and a cathode and an anode, I w

said anode comprising a stem extending outwardly of said envelope, a

acooling system for removing heat from said anode stem and transmitting the same exteriorlyof said housing comprising a fluid circulatory system inc d a v a radiator positioned exteriorly of said housing,

aheat exchanger operatively associated with said anode stem to extract heat from the latter,

anion drag pump comprising an emitter means and a collector means, I M v and. conduit means connecting said radiator, said heat exchanger and said ion drag pump in a. closed series cir cuit, sai d conduitmeans extending through the I housing walland being sealedlherein, a fluid of high dielectric strength filling said system,

and means in said housingfor supplying high voltage to said emitter means and collector means and to said cathode and anode. 5. An X-ray apparatus comprising a sealed housing, an X-ray tube in said housing,

saidX-ray tube comprising a sealed envelope and a cathode, and an anode,

awhigh voltage transformer in said housing for supplying accelerating. potential to said tube,

said anode comprising a stern extending outwardly. of

said envelope,

a cooling system for removing heat from said anode stem and transmitting the same exteriorly of said housing comprising a fluid circulatory system includa radiator positioned exteriorly of said housing,

a heat exchanger operatively associated with said anode stem to extract heat from the latter, anion drag pump comprising an emitter means and a collector me n v conduit means connecting said radiator, said heat ext hanger and said ion'drag pump in a closed series circuit, said conduit means extending through the housing wall and being sealedtherein, and

a fluid of high dielectric strength filling said system,

and means supplied from the secondary of said high voltage transformer for supplying a high D.C. voltage to saidemitter means and collector means.

6. An X-ray apparatus comprising an X-ray tube,

said tube comprising a sealed envelope and a cathode andan'; anode, a high voltage transformer supplying accelerating potential to said tube,

said anode comprising a stem extending outwardly of said envelope,

voltage transformer for supplying a high D.C. voltage to said emitter means and collector means.

References Cited in the file of this patent UNITED STATES PATENTS 1,992,335 Tietig Feb. 26, 1935 2,611,095 Goldfield Sept. 16, 1952 2,980,800 Steen Apr. 18, 1961 OTHER REFERENCES Dielectric Pump, by Busse, Popular Electronics, April 1959, pages 99 to 101. 

1. AN X-RAY APPARATUS COMPRISING AN X-RAY GENERATOR COMPRISING A CATHODE AND AN ANODE, A HIGH VOLTAGE TRANSFORMER FOR SUPPLYING ACCELERATING POTENTIAL TO SAID GENERATOR, A COOLING SYSTEM FOR REMOVING HEAT FROM SAID ANODE COMPRISING A FLUID CIRCULATORY SYSTEM INCLUDING A RADITATOR, A HEAT EXCHANGER OPERATIVELY ASSOCIATED WITH SAID ANODE TO EXTRACT HEAT FROM THE LATTER, AN ION DRAG PUMP COMPRISING AN EMITTER MEANS AND 